Clinched seam formation



Sept. 1965 w. c. BROOKSON 3,204,595

CLINCHED SEAM FORMATION Original Filed Aug. 2, 1960 f i A {d .4 A a"! 441 y a? 7 j J, 7- f IN V EN TOR.

W Z, 5. W/AZMM (WA/FA 5 5200/60 ATTORNEY United States Patent Ofl ice3,204,595 CLINCHED SEAM FORMATION William Charles Brookson, Hamilton,Untario, Canada, assignor to American Can Company, New York, N.Y., acorporation of New Jersey Original application Aug. 2, 1960, Ser. No.46,913, now Patent No. 3,053,409, dated Sept. 11, 1962. Divided and thisapplication Oct. 4, 1961', Ser. No. 146,685 3 Claims. (Cl. 113--121)This application is a division of application Serial No. 46,913, filedAugust 2, 1960, now US. Patent No. 3,053,- 409, granted September 11,1962.

The present invention relates to the clinching of can ends onto canbodies to facilitate the vacuumizing of double seamed cans prior to thefinal double seaming operation, and has particular reference to theformation of a clinched seam wherein conventional can body and endflanges are rolled together to interlock them in such manner as topositively prevent the lining compound which is carried on the endflange from seating on the body flange to hermetically seal off theinterior of the can.

In the canning of comminuted products such as powdered milk, groundcoflee and the like, it is necessary to remove as much as possible ofthe air which is entrapped within the can and the product containedtherein prior to the final double seaming operation in order to preventsubsequent deterioration of the product by oxidation. Removal of thisair is usually effected by placing the filled but unsealed can in aclosed chamber and subjecting the chamber to a high vacuum in order toevacuate the interior of the can.

In such vacuumizing operation, vacuums as high as 29.8 inches of mercurymay be employed. Since automatic equipment is usually employed, the timeduring which the evacuating process can be effected is necessarilylimited and the vacuum is created in the vacuum chamber in a relativelyshort time. As a result, there is a definite tendency for the air withinthe canto be drawn from the can with great velocity, and the resultantoutrush of air from the can, unless controlled, frequently carries withit a portion of the comminuted product.

Obviously, removal of the product from the can interior in such manneris very undesirable. In order to prevent it, the usual practice is toapply the can cover to the can body prior to the time the can isinserted into the vacuumizing chamber, and to provide for passageways ineither the body or the cover through which the air may be withdrawn,these passageways being carefully dimensioned to limit and control therate of withdrawal of the an.

A generally used method of providing such passageway is to secure thecan cover to the can body in a preliminary seaming operation wherein thecan body and end flanges are rolled together to form an incomplete,nonhermetic seam which is referred to as a clinched seam, this seamingoperation being known as clinching operation. No particular difficultyis encountered in the formation of such seams when a low vacuum is beingdrawn, inasmuch as it is possible to use clinched seams which are quiteloose and which provide relatively large passageways for the flow ofair, since a low vacuum does not pull the air from the can interiorviolently enough to carry the product with it. Such loosely clinchedseams can be easily formed without danger of creating a hermetic seamthrough which the air cannot pass. However, when very high vacuums arebeing utilized, the clinched seam must be relatively tight in order toprevent the air from being pulled from the can too rapidly, and there isthe ever present possibility that in tight seams the end lining compoundwill seat on the body flange and create a seal which is completelyhermetic, or so close to being hermetic as to effectively prevent thedesired withdrawal of the air from the container interior.

A relatively tight clinched seam is also advantageous for use withpacking processes wherein the vacuum within the can is replaced by aninert gas such as carbon dioxide or nitrogen, while the can is still inthe closed chamber, for in such processes it is a common practice tointroduce the can into the outside atmosphere prior to the final seamingoperation, and a tight clinched seam is necessary to prevent the inertgas from spilling out of the can and being replaced, in part at least,by the outside air during the transfer of the can from the vacuumizingand gassing chamber to the closing machine. The tighter the clinchedseam, the less chance there is: of such loss of inert gas.

The present invention provides a solution to this problem by providing amethod and apparatus for forming a clinched seam which positivelyinsures against seating of the end lining compound on the body flange toform a hermetic seal, and yet produces a seam which is tight enough tocontrol the flow of air from the can when high vacuums are being used.This is effected by tightly rolling spaced portions of the seam togetherin such manner that the end lining compound carried by the cover in suchspaced portions is pressed into engagement against the can body flange,thus locking the cover and can body together and holding them againstupward relative axial movement so that the seam does not open up to anundesirable extent when the can is subjected to external vacuum.However, the seam, between these tightly rolled portions, is formed withloosely rolled portions wherein the cover flange is lifted upwardly awayfrom the body flange in order to positively eliminate the possibility ofhaving the end lining com-pound in these portions seat upon the bodyflange. While in these loosely rolled areas there is metal-to-metalcontact between the contiguous portions of the can cover and can body,such contact is discontinuous because of the inherent irregularities inthe metal of these parts and is not effective in preventing the passageof the air through these portions of the seam.

The clinched seam is formed by a specially profiled, generally circularclinching roll which is provided with an endless clinching groove whichis radially non-concentric with the clinching roll axis in order tocreate the alternate loose and tight seam portions, and which, axiallyof the roll is of wavy or sinuous configuration so that it is providedwith a series of high spots which actually lift the cover flangeupwardly away from the body flange in the loose seam portions. As aresult of the fact that the cover flange is lifted away from the body inthe loosely formed seam portions, there is substantially no chance ofhaving the end lining compound in such areas seat on the body flange andpassage of air through the seam is always insured.

An object of the invention therefore is the provision of a method offorming a clinched seam wherein the seam is formed with alternatelyloosely and tightly rolled portions in such manner that the seating ofthe end lining compound in the loosely rolled portion is effectivelyprevented.

Still another object is the provision of a specially constructed seamingroll for effecting the formation of such a seam.

Numerous other objects and advantages of the invention will be apparentas it is better understood from the following description, which, takenin connection with the accompanying drawings, discloses a preferredembodiment thereof.

Referring to the drawings:

FIGURE 1 is a side elevation of a can having its cover secured in placein a clinched seam made according to the principles of the instantinvention, the view also showing Patented Sept. 7, 1965 in operativeposition relative to said can certain operating parts of a clinchingmachine, including a specially projected clinching roll which isdesigned to form the said clinched sea-n1;

FIG. 2 is a plan view of the clinched can and the clinching machineparts shown in FIG. 1;

FIG. 3 is a fragmentary vertical section on an enlarged scale takenthrough an upper peripheral portion of the can of FIGS. 1 and 2, butshowing the can end in assem'bled position on the can body preparatoryto the clinching operation;

FIG. 4 is a vertical section, on the same scale as FIG. 3, takensubstantially along the line 44 in FIG. 2, this view being taken throughthe loosely formed portion of the clinched seam, the view alsoincluding, in dot and dash linw, a vertical section taken through thecorresponding portion of the clinching roll which effects the formationof such loosely formed seam portion; and

FIG. 5 is a vertical section taken substantially along the line 5-5 inFIG. 2, this view being taken through a tightly rolled portion of theclinched seam and also showing in dot and dash lines a vertical sectiontaken through the corresponding portion of the clinching roll whichforms the tightly rolled seam portion.

As a preferred .and exemplary embodiment of the instant invention thedrawings illustrate a can of the conventional double seamed varietywhich comprises a tubular can body 12 preferably formed with aconventional side seam 14 and having its lower end closed by a recessedbottom end member 16 which is secured thereto in a conventional doubleseam 18. The can 10, after being filled with a suitable comminuted orpowdery product such as powdered milk (not shown), has applied to itsupper end a conventional cover member 20 of the type which is adapted tobe sealed to the body 12 in a conventional double seam.

In order to permit the formation of such a double seam, the can body 12is provided at its upper end with an outwardly extending annular flange22 which normally projects from the can body 12 in a generallyhorizontal plane, as best seen in FIG. 3. The cover member 20 isprovided with a depressed center panel 24 which at its outer edge mergesinto an upwardly extending annular wall 26 which in the trade isreferred to as a countersink wall. This countersink wall 26 in turnmerges into an annular, outwardly extending cover flange 28 which at itsouter edge is bent into a downwardly and inwardly extending curl 30. Theunderside of the cover flange 23 carries an end lining compound 32 whichnormally comprises a thin film of a rubbery material, which whencompressed between the cover flange 28 and body flange 22 in thefinished double seam (not shown), provides a hermetic seal.

When the cover member 20 is initially placed in position in the upperend of the can body 12, as best seen in FIG. 3, the end lining compound32 comes into loose contact with the upper surface of the body flange22. With these parts thus positioned, the filled can is fed into aclinching machine wherein the formation of the clinched sear-n of theinstant invention is effected. In such machine, the cover member 20 andcan body 12 are clamped together under pressure between a seaming chunk40, which is so shaped that it fits into the cover member 20 and engagesagainst the panel 24 and against the inner surface of the countersinkwall 26, and a lifter pad 42 which fits into the recessed bottom endmember 16.

After being thus clamped together, a clinching roll 44, made accordingto the principles of the instant invention, is moved radially of the canand brought into contact with the outer surface of the cover flange 28and curl 26 in order to reshape the cover flange 28 and body flange 22to form a clinched seam S, which tightly secures the cover member 20 inposition on the can body 12, but which is not hermetically sealed andthus permits the passage of air from the interior of the can when theclinched can is subsequently introduced int-o a vacuumizing chamber (notshown).

The clinching roll 44 is carried by a shaft 46 and is mounted for axialrotation, being either positively driven by the shaft 46 or idly affixedthereto. Suitable means are provided to effect a relativecircumferential movement of the rotating clinching roll 44 around theupper periphery of the can It) and cover 20 to thereby effect formationof the clinched seam S. This may be done either by moving the clinchingroll 44 bodily around the can 10 and cover 20, or by rotating the can14D and cover 20 on their own axes and maintaining a seaming roll shaft46 in a fixed position relative thereto.

As best seen in FIG. 1, the clinching roll 44 is formed with an upperannular shoulder 48, which extends inwardly over the cover flange 28,and a body portion 50 which is disposed immediately below said shoulder.An endless annular clinching groove 52 of special configuration is cutinto an outer periphery of the body portion 50. This clinching groove 52throughout its length is uniform in vertical cross-sectional contour asbest seen in FIGS. 4 and 5, but is generally sinuous or wavy as viewedin side elevation (see FIG. 1) and is formed with a plurality of evenlyspaced high portions 54 which are offset upwardly relative to theintervening low portions 56. The distance of offset is comparativelysmall, and may be in the nature of .025", although this figure may bevaried somewhat on either side and still produce the desired results.

In addition to its serpentine configuration, the groove 52 is irregularin that it is not concentric with the axis of the seaming roll 44, butis preferably formed of a plurality (here shown as three) of eccentricgroove segments 58 each of which extends around the clinching roll 44,thus forming what in effect is a three lobed groove. The eccentricity ofthe segments 58 is, however, comparatively minor so that they mergesmoothly into each other at their ends at points which are designated bythe letter B, the groove 52 at such points being at its maximum distancefrom the axis of the clinching roll 44 (as best seen in FIG. 2). Thetotal eccentricity of the segments 58 is not critical, but as example,there may be radial variations of approximately .055" in the groove 52of a roll wherein the diameter of the body portion 50 is approximately1.977. As best seen in FIG. 1, the body portion 50 is not actuallycircular but has a circumferential contour which is substantiallyparallel to the contour of the clinching groove 52, being formed ofthree eccentric segments which merge smoothly into each other.

The clinching groove 52 is formed so that there is a definiterelationship between its eccentricity and its sinuosity, the low spots56 of the groove 52 coinciding with the points E of greatest radiallength, and the high spots 54 lying midway between the points E andcoinciding with those portions of the groove 52 having the shortestradial length.

When the clinching roll 44 is moved inwardly against the flange 28 ofthe cover member 20, the clinching groove 52 reshapes this flange 28 toroll it downwardly and inwardly beneath the can body flange 22, and thismovement of the cover flange 28 in turn bends the body flange 22downwardly and inwardly, the result being that these flanges are rolledtogether and interlocked to form the clinched seam S of the instantinvention.

Because of the unusal configuration of the seaming groove 52, thisclinched seam is not formed of uniform tightness, but rather comprises aseries of loosely clinched portions, which will be hereinafter referredto by the letter L, and a series of tightly clinched portions which willhereinafter be referred to by the letter T, the portions L and T merginginto each other smoothly and evenly, as best seen in FIG. 1.

At the tightly clinched portions T, the can body and end flanges 22, 28are tightly rolled together in such manner that the end lining compound32 seats upon the body flange 22 as clearly seen in FIG. 5, thuseffecting a substantially hermetic seal at these portions.

The tight seam portions T are formed by the portions E of the clinchinggroove 52, because at such points the clinching groove 52 has itsgreatest radial length, and thus extends farthest towards the axis ofthe can body 12 and cover 20. Also, the portions E coincide with the lowspots 56 of the groove 52 and the combination of these two factorseifects the maximum reshaping of the can parts and in effect gives thetight seam portions T a contour which closely approximates that of afull first operation seam.

Laterally of the tight seam portions T, however, the cover flange 28 isgradually lifted upwardly away from the body flange 22 by the high spots54 of the clinching groove 52, and in addition, is rolled less tightlyin a lateral direction as the portions 54 of the clinching groove 52become operative. As a result, the lining compound 32 in such seamportions is positively lifted out of contact with the body flange 22,and is prevented from seating thereon. As seen in FIG. 4 the body flange22 may be reshaped slightly, even in the loose seam portions L, but isnevertheless maintained out of contact with the lining compound 28.

Thus, when the clinched can is placed in the vacuumizing chamber andsubjected to external vacuum, the air within the can passes easily andreadily through the loose seam portions L and the desired vacuum withinthe can is quickly obtained, despite the fact that metal-tometal contactbetween the can body and cover may be present in such loosely rollerportions.

It will be clear that the invention is not limited to a clinching rollwherein the lobes which form the tight seam portions T are formed byeccentric segments in the manner shown, but that the lobes may be formedin any manner, as long as the groove contains portions of difierentradial lengths. It will also be clear that the invention is not limitedto a three lobed clinching groove, but that a groove having one or morelobes will effect alternate loose and tight seam portions, the frequencyand spacing between such portions however, being determined by thenumber of lobes used. In every construction, however, the low portionsof the clinching groove will concide with the groove lobes, so thatthese portions of the groove will produce tight seam portions.

After the air has thus been removed from the can, it is necessary todissipate the vacuum Within the can in order to prevent its replacementby the external air if the clinched can is to be introduced into theoutside atmosphere prior to the final seaming operation. In such event,the vacuum in the chamber is replaced by an inert gas such as nitrogenor carbon dioxide which is held at substantially atmospheric pressure.Because of the high vacuum Within the can, such inert gas passes throughthe loose seam portions L and enters the can until it establishes asubstantially atmospheric pressure therewithin. Thereafter, the clinchedgassed can may be introduced into the external atmosphere, and then fedinto a closing machine wherein the final double seam is formed in theconventional manner. Because of the fact that the gas pressure within issubstantially in balance with the atmospheric pressure, and because thepassageways in the loosely seam portions L are restricted by themetal-tometal contact in such areas, there is substantially no tendencyfor the gas in the can to be replaced by the external air during thetime the can is being transferred from the chamber to the closingmachine, and thus the oxygen content of the finally seamed can is heldto a minimum.

It is thought that the invention and many of its attendant advantageswill be understood from the foregoing discription, and it will beapparent that various changes may be made in the form, construction andarrangement of the parts and in the steps of the method described andtheir order of accomplishment without departing from the spirit andscope of the invention or sacrificing all of its material advantages,the form hereinbefore described being merely a preferred embodimentthereof.

I claim:

1. The method of forming a clinched seam, which comprises the steps ofclamping a flanged can end having sealing material thereon and a flangedcan body together, rolling the flanges of said can end and said can bodytoether to produce alternating loosely rolled seam portions, and tightlyrolled seam portions wherein said can end flange and said sealingmaterial thereon are maintained in engagement with said can body flange,and simultaneously lifting said can end flange in said loosely rolledseam portions to move said sealing material thereon out of engagementwith said can body flange.

2. The method of forming a clinched seam which comprises the steps ofclamping a flanged can end having sealing material thereon and a flangedcan body together, rolling said flanges together to interlock them, andsimultaneously imparting an axially sinuous configuration to saidflanges to produce tightly interlocked flange portions wherein said canend flange and said sealing material thereon are maintained inengagement with said can body flange, and loosely interlocked flangeportions wherein the portion of said can end flange having said sealingmaterial thereon is axially spaced from said can body flange to preventa hermetic seal between said flanges in said loosely interlocked flangedportions.

3. The method of claim 2 wherein said loosely interlocked flangeportions are so formed that said can end flange is disposed inengagement with the end portion of said can body flange in said looselyinterlocked portions.

References Cited by the Examiner UNITED STATES PATENTS 1,160,055 11/15Dorland 113 23 1,367,953 2/21 Englund 113 23 1,476,213 12/23 OBrien 113-1,689,641 10/23 Pickles 113-120 1,766,173 6/30 Hills 113- 120 2,455,73712/48 COyle .113 120 2,643,627 6/53 Wobbe "113-120 CHARLES W. LANHAM,Primary Examiner. WHITMORE A. WILTZ, Examiner.

1. THE METHOD OF FORMING A CLINCHED SEAM, WHICH COMPRISES THE STEPS OFCLAMPING A FLANGES CAN END HAVING SEALING MATERIAL THEREON AND A FLANGEDCAN BODY TOGETHER, ROLLING THE FLANGES OF SAID CAN END AND SAID CAN BODYTOGETHER TO PRODUCE ALTERNATING LOOSELY ROLLED SEAM PORTIONS, ANDTIGHTLY ROLLED SEAM PORTIONS WHEREIN SAID CAN END FLANGE AND SAIDSEALING MATERIAL THEREON ARE MAINTAINED IN ENGAGEMENT WITH SAID CAN BODYFLANGE, AND SIMULTANEOUSLY LIFTING SAID CAN END FLANGE IN SAID LOOSELYROLLED SEAM PORTIONS TO MOVE SAID SEALING MATERIAL THEREON OUT OFENGAGEMENT WITH SAID CAN BODY FLANGE.